From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:36954) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UJ1Xo-0007xV-MV for qemu-devel@nongnu.org; Fri, 22 Mar 2013 08:58:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UJ1Xm-0000fN-3F for qemu-devel@nongnu.org; Fri, 22 Mar 2013 08:58:04 -0400 Received: from [2a02:248:0:30:223:aeff:fefe:7f1c] (port=45980 helo=dns.kamp-intra.net) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UJ1N4-0005ZS-CQ for qemu-devel@nongnu.org; Fri, 22 Mar 2013 08:46:58 -0400 From: Peter Lieven Date: Fri, 22 Mar 2013 13:46:04 +0100 Message-Id: <1363956370-23681-4-git-send-email-pl@kamp.de> In-Reply-To: <1363956370-23681-1-git-send-email-pl@kamp.de> References: <1363956370-23681-1-git-send-email-pl@kamp.de> Subject: [Qemu-devel] [PATCHv4 3/9] buffer_is_zero: use vector optimizations if possible List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: quintela@redhat.com, Stefan Hajnoczi , Peter Lieven , Orit Wasserman , Paolo Bonzini performance gain on SSE2 is approx. 20-25%. altivec is not tested. performance for unsigned long arithmetic is unchanged. Signed-off-by: Peter Lieven Reviewed-by: Eric Blake --- util/cutils.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/util/cutils.c b/util/cutils.c index 41c627e..0f43c22 100644 --- a/util/cutils.c +++ b/util/cutils.c @@ -205,6 +205,11 @@ bool buffer_is_zero(const void *buf, size_t len) long d0, d1, d2, d3; const long * const data = buf; + /* use vector optimized zero check if possible */ + if (can_use_buffer_find_nonzero_offset(buf, len)) { + return buffer_find_nonzero_offset(buf, len) == len; + } + assert(len % (4 * sizeof(long)) == 0); len /= sizeof(long); -- 1.7.9.5